/**
     * Get a path from the local FS. If size is known, we go round-robin over the set of disks (via
     * the configured dirs) and return the first complete path which has enough space.
     *
     * <p>If size is not known, use roulette selection -- pick directories with probability
     * proportional to their available space.
     */
    public synchronized Path getLocalPathForWrite(
        String pathStr, long size, Configuration conf, boolean checkWrite) throws IOException {
      confChanged(conf);
      int numDirs = localDirsPath.length;
      int numDirsSearched = 0;
      // remove the leading slash from the path (to make sure that the uri
      // resolution results in a valid path on the dir being checked)
      if (pathStr.startsWith("/")) {
        pathStr = pathStr.substring(1);
      }
      Path returnPath = null;
      Path path = new Path(pathStr);

      if (size == SIZE_UNKNOWN) { // do roulette selection: pick dir with probability
        // proportional to available size
        long[] availableOnDisk = new long[dirDF.length];
        long totalAvailable = 0;

        // build the "roulette wheel"
        for (int i = 0; i < dirDF.length; ++i) {
          availableOnDisk[i] = dirDF[i].getAvailable();
          totalAvailable += availableOnDisk[i];
        }

        // Keep rolling the wheel till we get a valid path
        Random r = new java.util.Random();
        while (numDirsSearched < numDirs && returnPath == null) {
          long randomPosition = Math.abs(r.nextLong()) % totalAvailable;
          int dir = 0;
          while (randomPosition > availableOnDisk[dir]) {
            randomPosition -= availableOnDisk[dir];
            dir++;
          }
          dirNumLastAccessed = dir;
          returnPath = createPath(path, checkWrite);
          if (returnPath == null) {
            totalAvailable -= availableOnDisk[dir];
            availableOnDisk[dir] = 0; // skip this disk
            numDirsSearched++;
          }
        }
      } else {
        while (numDirsSearched < numDirs && returnPath == null) {
          long capacity = dirDF[dirNumLastAccessed].getAvailable();
          if (capacity > size) {
            returnPath = createPath(path, checkWrite);
          }
          dirNumLastAccessed++;
          dirNumLastAccessed = dirNumLastAccessed % numDirs;
          numDirsSearched++;
        }
      }
      if (returnPath != null) {
        return returnPath;
      }

      // no path found
      throw new DiskErrorException("Could not find any valid local " + "directory for " + pathStr);
    }
예제 #2
0
  /**
   * Get the locally cached file or archive; it could either be previously cached (and valid) or
   * copy it from the {@link FileSystem} now.
   *
   * @param cache the cache to be localized, this should be specified as new
   *     URI(hdfs://hostname:port/absolute_path_to_file#LINKNAME). If no schema or hostname:port is
   *     provided the file is assumed to be in the filesystem being used in the Configuration
   * @param conf The Confguration file which contains the filesystem
   * @param subDir The sub cache Dir where you want to localize the files/archives
   * @param fileStatus The file status on the dfs.
   * @param isArchive if the cache is an archive or a file. In case it is an archive with a .zip or
   *     .jar or .tar or .tgz or .tar.gz extension it will be unzipped/unjarred/untarred
   *     automatically and the directory where the archive is unzipped/unjarred/untarred is returned
   *     as the Path. In case of a file, the path to the file is returned
   * @param confFileStamp this is the hdfs file modification timestamp to verify that the file to be
   *     cached hasn't changed since the job started
   * @param fileLength this is the length of the cache file
   * @param currentWorkDir this is the directory where you would want to create symlinks for the
   *     locally cached files/archives
   * @param honorSymLinkConf if this is false, then the symlinks are not created even if conf says
   *     so (this is required for an optimization in task launches
   * @param lDirAllocator LocalDirAllocator of the tracker
   * @return the path to directory where the archives are unjarred in case of archives, the path to
   *     the file where the file is copied locally
   * @throws IOException
   */
  private static Path getLocalCache(
      URI cache,
      Configuration conf,
      Path subDir,
      FileStatus fileStatus,
      boolean isArchive,
      long confFileStamp,
      long fileLength,
      Path currentWorkDir,
      boolean honorSymLinkConf,
      MRAsyncDiskService asyncDiskService,
      LocalDirAllocator lDirAllocator)
      throws IOException {
    String key = getKey(cache, conf, confFileStamp);

    CacheStatus lcacheStatus;
    Path localizedPath;
    synchronized (cachedArchives) {
      lcacheStatus = cachedArchives.get(key);
      if (lcacheStatus == null) {
        // was never localized
        Path uniqueParentDir = new Path(subDir, String.valueOf(random.nextLong()));
        String cachePath = new Path(uniqueParentDir, makeRelative(cache, conf)).toString();
        Path localPath = lDirAllocator.getLocalPathForWrite(cachePath, fileLength, conf);
        lcacheStatus =
            new CacheStatus(
                new Path(localPath.toString().replace(cachePath, "")), localPath, uniqueParentDir);
        cachedArchives.put(key, lcacheStatus);
      }
      lcacheStatus.refcount++;
    }
    boolean initSuccessful = false;
    try {
      synchronized (lcacheStatus) {
        if (!lcacheStatus.isInited()) {
          localizedPath = localizeCache(conf, cache, confFileStamp, lcacheStatus, isArchive);
          lcacheStatus.initComplete();
        } else {
          if (fileStatus != null) {
            localizedPath =
                checkCacheStatusValidity(
                    conf, cache, confFileStamp, lcacheStatus, fileStatus, isArchive);
          } else {
            // if fileStatus is null, then the md5 must be correct
            // so there is no need to check for cache validity
            localizedPath = lcacheStatus.localizedLoadPath;
          }
        }
        createSymlink(conf, cache, lcacheStatus, isArchive, currentWorkDir, honorSymLinkConf);
      }

      // try deleting stuff if you can
      long size = 0;
      int numberSubDir = 0;
      synchronized (lcacheStatus) {
        synchronized (baseDirSize) {
          Long get = baseDirSize.get(lcacheStatus.getBaseDir());
          if (get != null) {
            size = get.longValue();
          } else {
            LOG.warn("Cannot find size of baseDir: " + lcacheStatus.getBaseDir());
          }
        }
        synchronized (baseDirNumberSubDir) {
          Integer get = baseDirNumberSubDir.get(lcacheStatus.getBaseDir());
          if (get != null) {
            numberSubDir = get.intValue();
          } else {
            LOG.warn("Cannot find subdirectories limit of baseDir: " + lcacheStatus.getBaseDir());
          }
        }
      }
      // setting the cache size to a default of 10GB
      long allowedSize = conf.getLong("local.cache.size", DEFAULT_CACHE_SIZE);
      long allowedNumberSubDir =
          conf.getLong("local.cache.numbersubdir", DEFAULT_CACHE_SUBDIR_LIMIT);
      if (allowedSize < size || allowedNumberSubDir < numberSubDir) {
        // try some cache deletions
        LOG.debug(
            "Start deleting released cache because"
                + " [size, allowedSize, numberSubDir, allowedNumberSubDir] ="
                + " ["
                + size
                + ", "
                + allowedSize
                + ", "
                + numberSubDir
                + ", "
                + allowedNumberSubDir
                + "]");
        deleteCache(conf, asyncDiskService);
      }
      initSuccessful = true;
      return localizedPath;
    } finally {
      if (!initSuccessful) {
        synchronized (cachedArchives) {
          lcacheStatus.refcount--;
        }
      }
    }
  }